Acropyga manuense LaPolla & Schneider, 2023

LaPolla, John S. & Schneider, Scott A., 2023, Trophobiosis between a new species of Acropyga (Hymenoptera, Formicidae) and new Neochavesia (Hemiptera, Xenococcidae) from Peru, and establishment of the Acropyga smithii species-group, ZooKeys 1154, pp. 1-16 : 1

Acropyga manuense LaPolla & Schneider sp. nov.

Figs 4-6 (worker), 7-8 (queen), 3 and 9-12 (male)

Description.

Worker (N = 10). Uniformly yellow; covered in a dense layer of pubescence including lateral portions of pronotum and mesopleuron; scattered erect setae across body. Head slightly longer than wide (CI: 90-99); posterior margin slightly concave medially; posterolateral corners rounded with ca. 6 erect setae found along margin; eyes small with uneven pigmentation (REL: 6-11); 8-segmented, incrassate antennae; scapes short of posterior margin by about ¼ to ½ length of pedicel (SI: 71-83); scapes with dense layer of pubescence and scattered erect setae across its length. Clypeus narrow (width in holotype = 0.113 mm) and medially convex. Mandibles with 4 distinct teeth; apical teeth are the longest; teeth 2 and 3 are about equal in size and basal tooth is slightly smaller than teeth 2 and 3; a slight diastema exists between tooth 3 and the basal teeth. In lateral view, mesosoma profile of pronotum steeply rising toward mesonotum (ca. 45° angle if a line is drawn parallel to mesosomal venter). Posterior portion of pronotum and remainder of mesosomal notum with scattered erect setae of varying heights. Highest portion of mesonotum slightly higher than propodeum. Metanotal area distinct with length in holotype = 0.061 mm. Dorsal face of propodeum flat with length in holotype = 0.122 mm; declivitous face steep (ca. 75° angle). Petiole thick and erect with rounded apex; last ¼ of petiole surpasses the most dorsal portion of the propodeal spiracle. Gaster typical of Acropyga with thick layer of pubescence and scattered erect setae. Measurements (N = 8). HW: 0.432-0.489; HL: 0.46-0.531; EL: 0.031-0.057; ML: 0.467-0.583; PW: 0.277-0.329; PFL: 0.326-0.413; HL+ML: 0.927-1.09.

Queen (N = 4). As in worker with modifications expected for caste and with the following differences: CI: 95-100; SI: 78-87; REL: 26-32. Measurements (N =3). HW: 0.524-0.59; HL:0.55-0.59; EL: 0.147-0.188; ML: 0.844-1.03; PW: 0.531-0.606; PFL: 0.428-0.454; HL+ML: 1.4-1.62.

Male (N = 4). Head yellowish-brown, excluding mandibles and funicular segments which are yellow; remainder of body yellow. Head about as long as wide (CI: 99-108); posterior margin slightly rounded; medially with three prominent ocelli just anterior to posterior margin; posterolateral corners rounded with an indistinct angle and 2-3 erect setae. Compound eyes large, surpassing head margin in full-frontal view (REL: 34-40). 9-segmented incrassate antennae; scapes surpass posterior margin by about length of antennal pedicel (SI: 93-97); scapes covered with dense pubescence and widely scattered short erect setae. Clypeus medially convex (clypeal width in paratype USNMENT01130437 = 0.08 mm long); mandible with three teeth, large apical tooth and two smaller teeth at the basal angle; on some mandibles the two smaller teeth appear to have fused at the basal angle rendering the mandible 2-toothed. Mesosoma covered with dense pubescence and scattered short erect setae on mesoscutum and mesoscutellum. Pronotum small and collar-like with overarching large, rounded mesonotum. Mesoscutellum slightly higher than mesoscutellum in lateral view. Propodeum lower than mesonotum with no separation into dorsal and declivitous faces; propodeum flat (paratype USNMENT01130437 = 0.212 mm long) with a slight slope toward petiole. Petiole thick and erect just surpassing the lowest portion of the propodeum in lateral view. Gaster typical of male Acropyga with thick layer of pubescence and scattered erect setae. Gonopods in lateral view tapered to a rounded apex (paratype USNMENT01130437 gonopod length = 0.216 mm long); in dorsal view gonopods medially expanded. Cuspi tubular (paratype USNMENT01130437 = 0.094 mm long); where cuspi meet digiti several peg-like teeth span the surface; several setae extend off of cuspi apex as well; digiti tubular before a distinct right angle bending ventrally where they meet the cuspi; ventral facing portion of digiti taper toward apex becoming needle-like (paratype USNMENT01130437 = 0.108 mm long); apex of digiti visible beyond ventral margin of gonopod in lateral view. Penial sclerites elongate (Fig. 3 ); ventral margin curves from apex through rounded posterior region; along rounded section of penial sclerites margin dentate; apodeme located medially on anterior end of penial sclerites; apex of penial sclerites bend toward gonopods. Measurements (N =3). HW: 0.389-0.399; HL: 0.36-0.4; EL: 0.128-0.155; ML: 0.663-0.692; PW: 0.465-0.494; PFL: 0.412-0.451; HL+ML: 1.04-1.08.

Material examined.

Holotype: Peru • worker; Madre de Dios, Las Cruces, Manu Paradise Lodge , nest behind lodge, in soil around small rotting branches; 13.055°S, 71.544°W; 31.v.2019; J.S. LaPolla and S.A. Schneider leg.; USNMENT01130435 (UNMSM) . Paratypes: Peru • same data as holotype; 9 paratype workers: USNMENT01130438 (USNM), USNMENT01130439 (USNM), USNMENT01130450 (USNM), USNMENT01130451 (USNM), USNMENT01130452 (USNM), USNMENT01130453 (USNM), USNMENT01130454 (USNM), USNMENT01130465 (USNM), USNMENT01130483 (USNM); paratype queens: USNMENT01130436 (USNM), USNMENT01130467 (USNM), USNMENT01130468 (USNM), USNMENT01130480 (USNM); paratype males: USNMENT01130437 (USNM), USNMENT01130466 (USNM), USNMENT01130481 (USNM), USNMENT01130482 (USNM) .

Etymology.

The epithet is a noun in apposition, referring to its type location near Manu National Park, Peru.

Remarks.

The workers of A. manuense are similar in overall appearance to both A. fuhrmanni and A. smithii with all three possessing 8 antennal segments (although A. smithii workers can occasionally be found with as few as 7 segments) and 4 mandibular teeth. One of the most obvious ways A. manuense workers differ from both A. fuhrmanni and A. smithii workers is in mesosomal pubescence. In A. manuense workers possess thick pubescence that extends down the lateral portions of the pronotum and onto the mesopleuron. In A. fuhrmanni and A. smithii pubescence is very sparse to lacking on the lateral portions of the pronotum and the mesopleuron.

Several measurements will also allow for separation of the three species. The smallest of the three species is A. smithii with a head width and length less than 0.4 mm, whereas both A. fuhrmanni and A. manuense have head widths and lengths greater than 0.4 mm. The scape length in A. smithii is less than 0.27 mm, while it is greater than 0.3 mm in both A. fuhrmanni and A. manuense . The small size of A. smithii makes it fairly easy to distinguish from both A. fuhrmanni and A. manuense . Workers of A. fuhrmanni and A. manuense possesses different eye sizes with a relative eye length index between 12-15 in A. fuhrmanni and between 6-11 in A. manuense (Fig. 13 ). The cephalic index is also instructive with A. fuhrmanni generally having a value over 100 with A. manuense less than 100.

The most striking differences between A. fuhrmanni , A. smithii and A. manuense are found in males. The mandibles of the three species’ males differ in the number and size of teeth, with A. manuense possessing three distinct equally sized teeth. Both A. fuhrmanni and A. smithii only have two teeth: a prominent apical tooth and a much smaller tooth at the basal angle. There are several genitalic differences between the three species such as each possessing uniquely shaped penial sclerites (Figs 1-3 ). The digitus is very distinctive within A. manuense , being ventrally directed, elongated and coming to a prominent point (Figs 9 , 11 ). The elongated, pointed structure of the digitus is unique among all Acropyga species.

In the key to New World workers provided by LaPolla (2004), specimens of A. manuense will key to the lug for A. fuhrmanni . That lug would become a new couplet as follows:

1	Lateral portions of pronotum and mesopleuron with spare to no pubescence; ocular index between 12-15; cephalic index above 100	Acropyga fuhrmanni (Forel)
-	Lateral portions of pronotum and mesopleuron with thick layer of pubescence; ocular index between 6-11; cephalic index less than 100	Acropyga manuense LaPolla & Schneider, sp. nov.

Figures

Figure 13. Bivariate plot of eye length vs. head length among measured A. fuhrmanni, A. manuense and A. smithii workers.

Figures 4 - 6. Acropyga manuense sp. nov., worker USNMENT 01130435 (holotype) 4 lateral view 5 full-face view 6 dorsal view.

Figures 1 - 3. Dissected penial sclerites of various species in ectal view. Scale bar: Acropyga fuhrmanni and Acropyga smithii = 0.03 mm; Acropyga manuense = 0.05 mm.

Figures 9 - 12. Acropyga manuense sp. nov., male USNMENT 01130437 9 lateral view 10 full-face view 11 ventral view of genitalia 12 dorsal view of genitalia.